Role of air-sea interaction in propagation of early morning precipitation over the northern coast of West Java

• Main Author: Yulihastin, Erma
• Format: Conference Proceeding
• Language: English
• Subjects: Coastal zone; Coasts; Convection; Precipitation; Propagation; Rainfall; Surface wind; Weather forecasting
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0108085

Previous studies have shown that the peak in early morning precipitation (EMP) over the northern coast of West Java has a strong propagation characteristic and is formed by the interaction between local circulation and synoptic conditions involving the Cross-Equatorial Northerly Surge (CENS) and South China Sea Cold Tongue (SCSCT) phenomena. In addition, the propagation of EMP is determined by the initial location and its direction and speed of propagation. This study investigates the relationship between CENS and SCSCT and their role in determining the initial convection and its direction associated with EMP propagation by conducting numerical experiments based on real events using the Weather and Research Forecasting (WRF) model with a convection-permitting resolution of 3 km. The results show that, when the CENS coincides with the SCSCT, EMP is concentrated and expands over the coastal region owing to the formation of a strong and persistent convergence between the land breeze and background winds. In this scenario, the SCSCT plays a role in strengthening surface winds over the Karimata Strait (4°S-2°N, 105°-115°E) and producing the local CENS. When a CENS-SCSCT event occurs, the CENS modulates the surface wind in both the SCSCT and CENS index areas, with reinforcing low-level flows developing southward over the Java Sea. [Please check this revision.] In addition, the CENS plays a major role in changing the EMP propagation by changing both the timing and propagation patterns, whereas the SCSCT influences only the timing of the rainfall. The results also suggest that CENS-SCSCT strengthens the monsoon circulation (at 850 and 200 mb) and increases the updraft over the coastal area. As a result, the EMP becomes more intense, more persistent, and extends across both the land and sea in the coastal region.